JP2002205510A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having improved uniformity by constituting a carcass layer by dispersing joint parts between band-like carcass materials randomly on the periphery of the tire. SOLUTION: Three or more kinds of band-like carcass materials 1 that are formed by covering a carcass cord 2 with coat rubber 3, are orthogonal to the carcass cord 2, and have different width directional lengths M are arranged randomly on one circle of the tire so that the carcass cord 2 cross the circumference direction, and side parts 4 and 4' in the tire circumference direction are joined to each other, thereby forming the carcass layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a pneumatic tire having an improved tire.

[0002]

2. Description of the Related Art In a conventional pneumatic tire, a plurality of strip-shaped carcass members formed by coating a plurality of carcass cords arranged in parallel with each other with a coating rubber are applied to a carcass layer over one circumference of the tire. Some are configured by being arranged continuously. But in this case,
Since the lengths in the width direction (corresponding to the tire circumferential direction lengths) of the strip-shaped carcass materials are the same, a plurality (tentatively, n) of joined portions of the strip-shaped carcass materials are present at equal intervals on the tire circumference. As a result, there is a problem that the nth-order uniformity-variation component per one rotation of the tire is deteriorated, which causes vehicle vibration and noise.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to form a carcass layer by randomly dispersing joints between strip-shaped carcass materials around a tire to form a uniform carcass layer.
It is to provide a pneumatic tire with improved.

[0004]

The pneumatic tire of the present invention comprises three or more belt-shaped carcass members formed by coating a carcass cord with a coating rubber and having different lengths in the width direction perpendicular to the carcass cord. The carcass layer is formed by randomly arranging the cords around the circumference of the tire so as to intersect with the tire circumferential direction, and joining the side portions in the tire circumferential direction to each other to form a carcass layer.

In the design of the tire tread surface, if grooves (lug grooves) extending in the tire width direction are arranged at equal intervals in the tire circumferential direction, the frequency range of “total number of lug grooves × the number of tire revolutions per second” is obtained. It is known that the sound pressure of the sound increases. In order to avoid this increase in sound pressure, conventionally, lug grooves are provided with several types of intervals in the tire circumferential direction, and the lug grooves are arranged discontinuously on the tire circumference to suppress noise generation.

In view of this point, according to the present invention, the width of the strip-shaped carcass material is varied as described above, and the strip-shaped carcass material is arranged randomly (that is, without regularity) over one circumference of the tire. There are n pieces of joints between the strip-shaped carcass materials are randomly dispersed on the tire circumference, so that the n-th order component of the uniformity is compared to the case where n pieces of joints exist at equal intervals on the tire circumference. The level can be suppressed, and the uniformity can be improved.

[0007]

FIG. 1 is a plan view showing an example of a strip-shaped carcass material. In FIG. 1, a band-shaped carcass material 1 is formed by arranging a plurality of carcass cords 2 in parallel with each other and covering these carcass cords 2 with a coating rubber 3.

The carcass cord 2 is, for example, an organic fiber cord such as a polyester cord, a rayon cord, an aromatic polyamide fiber cord, or an inorganic fiber cord such as a steel cord. The coating rubber 3 may be a usual rubber composition constituting a carcass layer.

In the pneumatic tire of the present invention, three or more belt-shaped carcass materials 1 having different lengths M in the width direction orthogonal to the carcass cord 2 are combined with the tire 1 so that the carcass cord 2 intersects the tire circumferential direction. A carcass layer is formed by arranging the tires at random over the circumference and joining the side portions in the tire circumferential direction to each other. In other words, in other words, as shown in FIG. 2 which is a developed view showing a state in which the band-shaped carcass material is arranged on the peripheral surface of the molding drum, the band-shaped carcass material 1 is connected to the carcass cord 2 by the circumferential direction T (tire). (Corresponding to the circumferential direction) and are randomly arranged over one circumference of the forming drum. Then, the side portion 4 of the carcass material 1 in the circumferential direction T,
4 'are joined together. Thereby, the n joints are randomly distributed on the tire circumference. The intersection angle of the carcass cord 2 with respect to the tire circumferential direction is preferably approximately 90 °, but may be 90 ° to 70 °.

The joint may be made by abutting the sides 4, 4 'together (butt joint) or by overlapping the sides 4, 4' together (lap splice).

The reason why three or more kinds of band-shaped carcass materials 1 are used is as follows.
This is because in the case of the two types, the joints are difficult to be randomly dispersed on the tire circumference. Also, preparing various kinds of strip-shaped carcass materials is a factor of inhibiting productivity. Therefore, it is preferable to use three to five types.

Further, it is preferable that the width direction length of one strip-shaped carcass material among the strip-shaped carcass materials does not become an integral multiple of the width direction length of the other strip-shaped carcass material. This is because when the number is an integral multiple, the frequencies are synchronized and noise is easily generated.

The number of strip-shaped carcass materials is preferably 7 or more, and more preferably 9 to 12. this is,
In order to suppress the n-th order uniformity-variation component per tire rotation, it is possible to reduce to a certain level by not giving regularity to the joining order of the band-shaped carcass material as described above. Have no (or n
In other cases, the level of the n-th order is inevitably high for other objects, and the vibration and noise are caused by low-order uniformity fluctuations of the order of 1 to 6 orders per tire rotation. Because there are many.

Further, the ratio (K / L) of the maximum width direction length K to the minimum width direction length L among the width direction lengths M of the three or more belt-shaped carcass materials is 1.5 or more. It is preferably 1.7 or more, and specifically, 1.7 to 2.2.
(Excluding an integral multiple of 2.0).

[Example] Tire size 175 / 70R1
The conventional tire 1 and the present invention tire 1 having the same 484S were manufactured under the following conditions.

Conventional tire 1 Number of joints between belt-shaped carcass members: 7 Number of band-shaped carcass members: 7 (the width direction length M of each belt-shaped carcass material is the same) One width direction of one belt-shaped carcass material Length M: 173.7 mm Forming drum circumference: M × number of joints = 173.7 mm × 7 = 1216 mm

Tire 1 according to the present invention Number of joints between belt-shaped carcass members: 7 Number of band-shaped carcass members: 7 (Three types of band-shaped carcass materials having different width-wise lengths M, a, b, c) (2 sheets, 3 sheets of b, 2 sheets of c)) Length M in the width direction of the band-shaped carcass material a: 121.6 mm... A Length M in the width direction of the band-shaped carcass material b: 173.7 mm. Carcass material c width direction length M: 225.8 mm ... C forming drum circumference: number of A x a + number of B x b + number of C x c 121.6 mm x 2 + 173.7 mm x 3 + 225.8 mm x 2 = 1216mm Uniformity of these tires under the following conditions
Was measured. The result is shown in FIG.

Uniformity- JASO conditions. Measurement rim: 14 × 5J, measurement load: 37
5 kg, measured air pressure; 200 kPa.

As can be seen from FIG. 3, the tire 1 of the present invention has a lower uniformity level in the seventh order component (the number of joints) than the conventional tire 1 (fluctuation in the radial force of the tire ( RFV), uniformity
It is clear that it is excellent.

[0020]

As described above, in the pneumatic tire of the present invention, three or more kinds of strip-shaped carcass members formed by coating a carcass cord with a coating rubber and having different lengths in the width direction orthogonal to the carcass cord, Carcass cords are randomly arranged around the circumference of the tire so as to intersect with the tire circumferential direction, and the carcass layer is formed by joining the side parts in the tire circumferential direction to each other, so that uniformity can be improved. Becomes

[Brief description of the drawings]

FIG. 1 is a plan view of an example of a band-shaped carcass material.

FIG. 2 is a development view showing a state in which a belt-shaped carcass material is arranged on a peripheral surface of a forming drum.

FIG. 3 is a relationship diagram between an n-order component and a uniformity level.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 strip-shaped carcass material 2 carcass cord 3 coated rubber 4 side portion of strip-shaped carcass material 4 'side portion of strip-shaped carcass material

Claims (4)

[Claims] 1. A carcass cord formed by coating a carcass cord with a coating rubber and having at least three kinds of strip-shaped carcass materials having different lengths in a width direction orthogonal to the carcass cord, so that the carcass cord intersects the tire circumferential direction. A pneumatic tire in which a carcass layer is formed by arranging randomly around the circumference of a tire and joining side portions in a tire circumferential direction to each other. 2. The pneumatic tire according to claim 1, wherein the length in the width direction of one of the strip-shaped carcass materials is not an integral multiple of the length in the width direction of the other strip-shaped carcass material. 3. The pneumatic tire according to claim 1, wherein the number of the band-shaped carcass materials is seven or more. 4. A ratio (K / K / L) of a maximum width direction length K and a minimum width direction length L among the width directions of the strip-shaped carcass material.
The pneumatic tire according to claim 1, 2 or 3, wherein L) is 1.5 or more.